This invention relates to an exposure apparatus and, more particularly, to a projection exposure apparatus including an adjustable holder mechanism that controllably adjusts positions of an optical element and a plurality of aperture stops relative to each other and to the optical axis.
When manufacturing, for example, a semiconductor integrated circuit or liquid crystal substrate using a lithography technique, a resist film formed on a sample substrate is exposed into a predetermined pattern. In this exposure process, a projection exposure apparatus is generally used.
A projection exposure apparatus illuminates a reticle (mask), on which a prescribed circuit pattern is formed, with illumination light emitted from a light source. When the illumination light passes through the reticle, an image of the reticle pattern is formed. The reticle pattern image is projected through a projection optical system onto the resist film on the sample substrate. Thus, the resist film is exposed into the prescribed circuit pattern.
Recently, in connection with this type of projection exposure apparatus, many proposals have been made to make uniform an intensity distribution of illumination light that is guided to the reticle. For example, it has been proposed to provide an optical element called a fly-eye lens in the optical path of illumination light between the light source and the reticle. Japanese patent application laid-open No. 5-175100 discloses aperture stops positioned directly behind the fly-eye lens in an interchangeable manner, and one of the aperture stops is selected as necessary to chance the illumination condition of illumination light guided to the reticle.
However, in the prior art, even if a fly-eye lens is provided in the illumination optical system, which extends from the light source to the reticle, and even if interchangeable aperture stops are positioned immediately after the fly-eye lens, there is no consideration given to the positional relationship between the fly-eye lens and the aperture stop.
In recent years, improved exposure accuracy is demanded as the exposure pattern becomes smaller. To this end, it becomes necessary to maintain the stability of the positional relationship between the fly-eye lens and the aperture stop.